1. Field of the Invention
The present invention relates to electron beam apparatus used for automated inspection, or review, or metrology.
2. Description of the Background Art
It is often desirable to detect certain types of electrical defects in semiconductor wafers that have leakage due to electrical capacitance and resistance. Conventionally, such electrical defects are detected during electron beam (e-beam) inspection in one of two techniques.
In a first conventional technique, an electron probe beam is directed onto the substrate without pre-charging the substrate. The secondary electron signal is detected and analyzed in an attempt to determine the state of the interface.
In a second conventional technique, the substrate is pre-charged by flooding a relatively large area with an electron beam for an initial time period on the order of minutes (typically, a few minutes). The flooding is configured to provide a) a controlled voltage state for inspection uniformity across the spatial extent of one wafer or multiple wafers and/or b) a proper voltage state so that a subsequent probe step may actually detect the electrical defect of interest. After the flooding step, an electron probe is directed onto the substrate. Generally, there is some delay between the flooding step and the probe step which may be on the order of seconds (typically, a several seconds).